<template>
  <div>
    <!-- 评论列表 -->
    <div
      class="cmt-list"
      :class="sendShow ? 'art-cmt-container-1' : 'art-cmt-container-2'"
    >
      <van-list
        v-model="loading"
        :finished="finished"
        finished-text="没有更多了"
        @load="onLoad"
      >
        <!-- 评论的 Item 项 -->
        <div class="cmt-item" v-for="(item,index) in arr" :key="index">
          <!-- 头部区域 -->
          <div class="cmt-header">
            <!-- 头部左侧 -->
            <div class="cmt-header-left">
              <img :src="item.aut_photo" alt="" class="avatar" />
              <span class="uname">{{ item.aut_name }}</span>
            </div>
            <!-- 头部右侧 -->
            <div class="cmt-header-right">
              <van-icon
                v-if="item.is_liking === true"
                @click="likeFn(true, item)"
                name="like"
                size="16"
                color="red"
              />
              <van-icon
                v-else
                @click="likeFn(false, item)"
                name="like-o"
                size="16"
                color="gray"
              />
            </div>
          </div>
          <!-- 主体区域 -->
          <div class="cmt-body">
            {{ item.content }}
          </div>
          <!-- 尾部区域 -->
          <div class="cmt-footer">{{ formatTime(item.pubdate) }}</div>
        </div>
      </van-list>
    </div>

    <!-- 底部添加评论区域 - 1 -->
    <div class="add-cmt-box van-hairline--top" v-if="sendShow">
      <van-icon name="arrow-left" size="18" @click="$router.back()" />
      <div class="ipt-cmt-div" @click="showFn">发表评论</div>
      <div class="icon-box">
        <van-badge :max="99" :content="allCount > 0 ? allCount : ''">
          <van-icon name="comment-o" size="20" @click="moveFn" />
        </van-badge>
        <van-icon name="star-o" size="20" />
        <van-icon name="share-o" size="20" />
      </div>
    </div>

    <!-- 底部添加评论区域 - 2 -->
    <div class="cmt-box van-hairline--top" v-else>
      <textarea
       v-focus
        ref="area"
        @blur="blurFn"
        v-model="commentText"
        placeholder="友善评论、理性发言、阳光心灵"
      ></textarea>
      <van-button
        type="default"
        :disabled="commentText.length === 0"
        @click="sendFn(commentText)"
        >发布</van-button
      >
    </div>
  </div>
</template>

<script>
import { formatTime } from '@/utils/date.js'
export default {
  data () {
    return {
      sendShow: true, // 底部评论显示
      commentText: '', // 保存了评论内容
      loading: false,
      finished: false
    }
  },
  props: {
    arr: Array, // 评论数组
    allCount: Number // 评论总数
  },
  methods: {
    formatTime,
    // 点击 小爱心
    likeFn (bool, item) {
      this.$emit('like', bool, item)
    },
    // 点击发表评论切换输入框事件
    showFn () {
      this.sendShow = false
      // this.$nextTick(() => {
      //   //   输入框自动聚焦
      //   //   bool值改变 DOM更新是异步的,输入框挂载后再执行nextTick里的代码才能获取到输入框
      //   this.$refs.area.focus()
      // })
    },
    // 输入框失去焦点事件
    blurFn () {
      setTimeout(() => {
        this.sendShow = true
      })
    },
    // 发布事件
    sendFn (commentText) {
      // 失去焦点 - 用v-if和v-else,所以失去焦点时,DOM从DOM树上移除了,点击事件方法还没来得及触发
      //   console.log(this.commentText)
      this.$emit('sendFn', commentText)
      this.commentText = ''
    },
    // 点击移动到评论区
    moveFn () {
      // 点击评论小图标 - 要滚动到评论标签地方
      // 1.1 返回文档在垂直方向已滚动的像素值
      const now = window.scrollY
      // 1.2 目标位置（文章信息区域的高度）
      let dist = document.querySelector('.article-container').offsetHeight
      // 1.3 可滚动高度 = 整个文档的高度 - 浏览器窗口的视口（viewport）高度
      const avalibleHeight =
        document.documentElement.scrollHeight - window.innerHeight

      // 2.1 如果【目标高度】 大于 【可滚动的高度】
      if (dist > avalibleHeight) {
        // 2.2 就把目标高度，设置为可滚动的高度
        dist = avalibleHeight
      }

      // 3. 动态计算出步长值
      const step = (dist - now) / 10

      setTimeout(() => {
        // 4.2 如果当前的滚动的距离不大于 1px，则直接滚动到目标位置，并退出递归
        if (Math.abs(step) <= 1) {
          return window.scrollTo(0, dist)
        }
        // 4.1 每隔 10ms 执行一次滚动，并递归地进行下一次的滚动
        window.scrollTo(0, now + step)
        this.moveFn()
      }, 10)
    },
    // 触底加载更多
    onLoad () {
      this.$emit('more')
    }
  }
}
</script>

<style scoped lang="less">
.cmt-list {
  padding: 10px;
  .cmt-item {
    padding: 15px 0;
    + .cmt-item {
      border-top: 1px solid #f8f8f8;
    }
    .cmt-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      .cmt-header-left {
        display: flex;
        align-items: center;
        .avatar {
          width: 40px;
          height: 40px;
          background-color: #f8f8f8;
          border-radius: 50%;
          margin-right: 15px;
        }
        .uname {
          font-size: 12px;
        }
      }
    }
    .cmt-body {
      font-size: 14px;
      line-height: 28px;
      text-indent: 2em;
      margin-top: 6px;
      word-break: break-all;
    }
    .cmt-footer {
      font-size: 12px;
      color: gray;
      margin-top: 10px;
    }
  }
}
/*美化 - 文章详情 - 底部的评论页面 */
// 外层容器
.art-cmt-container-1 {
  padding-bottom: 46px;
}
.art-cmt-container-2 {
  padding-bottom: 80px;
}

// 发布评论的盒子 - 1
.add-cmt-box {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  box-sizing: border-box;
  background-color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 46px;
  line-height: 46px;
  padding-left: 10px;
  .ipt-cmt-div {
    flex: 1;
    border: 1px solid #efefef;
    border-radius: 15px;
    height: 30px;
    font-size: 12px;
    line-height: 30px;
    padding-left: 15px;
    margin-left: 10px;
    background-color: #f8f8f8;
  }
  .icon-box {
    width: 40%;
    display: flex;
    justify-content: space-evenly;
    line-height: 0;
  }
}

.child {
  width: 20px;
  height: 20px;
  background: #f2f3f5;
}

// 发布评论的盒子 - 2
.cmt-box {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 80px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12px;
  padding-left: 10px;
  box-sizing: border-box;
  background-color: white;
  textarea {
    flex: 1;
    height: 66%;
    border: 1px solid #efefef;
    background-color: #f8f8f8;
    resize: none;
    border-radius: 6px;
    padding: 5px;
  }
  .van-button {
    height: 100%;
    border: none;
  }
}
</style>
